misc: Remove redundant "use" imports

With the nightly toolchain (2024-02-18) cargo check will flag up
redundant imports either because they are pulled in by the prelude on
earlier match.

Remove those redundant imports.

Signed-off-by: Rob Bradford <rbradford@rivosinc.com>

arch/src/x86_64/mptable.rs

@@ -300,8 +300,7 @@ mod tests {
     use super::*;
     use crate::layout::MPTABLE_START;
     use vm_memory::{
-        bitmap::BitmapSlice, GuestAddress, GuestUsize, VolatileMemoryError, VolatileSlice,
-        WriteVolatile,
+        bitmap::BitmapSlice, GuestUsize, VolatileMemoryError, VolatileSlice, WriteVolatile,
     };
 
     fn table_entry_size(type_: u8) -> usize {